"Iran will get a jackpot, a cash bonanza of hundreds of billions of dollars which will allow it to continue to pursue its agenda of aggression and terror in the region and in the world," Netanyahu said. "This is a bad mistake of historic proportions."

Netanyahu has long criticized the talks with Iran, saying the deal threatens Israel's survival. Israel and others accuse Iran of fomenting unrest in the region.

In Syria, one of Iran's few regional allies, President Bashar Assad sent two cables to Iran's supreme leader, calling the agreement "a great victory" for the Islamic republic.

"Indubitably, this agreement crowns the steadfastness of the Iranian people, with all their components and inclinations, in the face of the unfair sanctions that were imposed on the Islamic Republic of Iran," he said. The comments were reported by the official news agency, SANA.

Assad has been isolated by the international community, and his country is in the throes of a bloody civil war. Iran has provided the Assad regime with military support during the conflict.

In Iraq, which like Iran is predominantly Shiite, a spokesman for Prime Minister Haider al-Abadi called the deal "a catalyst for regional stability." The comments were reported by The Associated Press.

Relations between the countries are so close that Iranian Revolutionary Guards are reportedly fighting alongside Shiite militias against the so-called Islamic State.

Mostly Sunni Saudi Arabia, which has been a harsh critic of the talks with Iran, has been muted in its official reaction, though Reuters quoted an unnamed Saudi diplomat as calling the agreement "extremely dangerous."

Badr Albusaidi, the general secretary of Oman's Ministry of Foreign Affairs, welcomed the deal in a tweet:

Oman was the intermediary through which U.S. and Iranian officials secretly exchanged messages in 2012 to lay the groundwork for the talks that led to Tuesday's deal.

Sheikh Khalifa bin Zayed Al Nahyan, the ruler of the United Arab Emirates, congratulated Iran on the deal, saying he hoped the agreement would "contribute to strengthening regional security and stability."